Story Mode is a game mode that was available in early versions of the original Killing Floor Mod and is currently available in Killing Floor: Incursion.

Both Story Modes involve progressing through levels in a sequential order to advance the plot, though Killing Floor: Incursion has multiple endings while the original mod only had one.

Story Mode was removed from later versions of the Killing Floor Mod as the game was retooled, and it's not clear how much -- if any -- of it's story is still canon.

A Story Mode was initially planned for the first retail Killing Floor, but it was eventually replaced by Objective Mode instead.